What am I doing?

[Mankito]

I am fiddling around then I start playing the open A string as a pedal note, then I play notes from the A Major scale on the 4th and 2nd strings down the neck, starting on the 9th fret,only the notes from this scale. It sounds nice as I end playing the E chord on the 1st position then finish the sequence with an open A chord. I realize I've been playing the diatonich chord sequence of that scale without actively thinking about it.
Then you can do the same with the open D string...and I suppose with the E string...
Then I just played the same A pedal note but this time playing only natural notes on any of the three first strings and I realized I ended up playing the C natural minor scale because the tonal note was A, isn't it?

I am not sure what I am asking here but I presume is the way the guitar is designed allows you to achieve this progressions, right?